From birth, infants have a natural sucking instinct or urge. This phenomenon is essential for the infants' survival, for it allows them to feed from the infant's mother's breast a short time following birth. However, if the sucking urge is not gratified, the infant will generally have a remaining urge that may lead either to frustration if the urge is not satisfied or the infant will lose the urge. A common practice to ease the frustration of the sucking urge is for the infant to engage in a non-nutritional sucking where the infant will suck a thumb, finger, or pacifier. Such acts may satisfy the urge. As a result of the satisfaction, such acts may provide a source of pleasure, self-gratification, comfort, and soothing relaxation. As the infant grows, the sucking urge is gradually replaced by mastication.
The use of a pacifier as a means to satisfy the sucking urge has been used for many centuries. In early pacifiers, the pacifiers were made of a cloth or chamois into which bread crumbs or sugar were placed and then were tied into the shape of a nipple. The end would be moistened and introduced in the infant's mouth. These simple devices over the years have evolved into the modern day pacifier, examples of which are shown in FIGS. 1A–1C.
Early conventional pacifiers, as shown in FIG. 1A, have a more cherry like nipple 4 and a convex shield 2 to conform to the infant's face. Physiological pacifiers, shown in FIGS. 1B and 1C have features that conform more to the infant's physical features. For example, the shields 12 and 22 have a concave shape that conforms more to the infant's face. Further, the nipples, 14 and 24, have designs to coexist with the infant's inter-oral structures, such as flattened to fit between the infant's teeth (shown in FIG. 1B) or an indented nipple to allow room for the infant's tongue (shown in FIG. 1C).
A problem associated with the use of these pacifiers is that after prolonged use, they begin to affect the development of or change the structure of the infant's oral cavity. Without the pacifier, thumb, finger, etc. in the mouth, the tongue naturally exerts a positive pressure in the mouth, namely a pressure pushing out against the alveolar ridges and the teeth. Such positive pressure spurs inter-canine and inter-molar distance growth of the teeth as well as spurs expansion of the width of the alveolar ridges.
When an infant sucks on one of these pacifiers, the top of the pacifier conforms to the roof of the infant's mouth, or palate, causing a negative pressure that is directed towards the midline of the roof of the child's mouth, or palate, and is exerted on the teeth and the bone surrounding the teeth, or the alveolar ridge, in the region of the upper deciduous canines and molar teeth. Such is shown in FIGS. 2A–2C. A conventional pacifier nipple 4 is placed into an infant's mouth, between a palate 8 having two sides, 5 and 6, about a center line CL, and a tongue 7. As tongue 7 moves upward during a sucking action, nipple 4 is compressed between the tongue and palate 8, forming a tremendous vacuum between the palate 8 and the pacifier 4. As tongue 7 moves down in the mouth during a sucking action, the vacuum pulls on palate sides 5 and 6 towards the centerline of palate 8, collapsing them inward. This pulling has an adverse effect on the inter-canine and inter-molar growth distance of the upper jaw, causing them to either move toward centerline CL of palate 8 or preventing the palate's natural growth outward, which can cause a cross bite, meaning the upper teeth bite on the inside of the lower teeth. This pulling can also cause the alveolar ridge, which generally has a horse shoe shape, to have a narrower width than normal. These adverse effects can overcome the natural growth caused by positive pressure from the tongue.
Other pacifiers have attempted to overcome the negative pressure created by the conventional pacifiers and re-create the tongue pressure, such as the pacifier disclosed in U.S. Pat. No. 5,922,010 (Alanen et al.), incorporated herein by reference in its entirety. In this pacifier, the nipple has a generally vertically concave shape, which contacts between the alveolar ridge near the base of the deciduous teeth on each side of the baby's mouth and the baby's tongue. During a baby's sucking action, the pressure applied by the tongue against the pacifier is transferred directly against the alveolar ridge and deciduous teeth to push them outward. However, the disadvantage of this pacifier is that with overuse of this pacifier, or use by an infant that did not need such a pacifier, the pressure pushing out on the teeth and alveolar ridge would cause a lateral horizontal gap between the posterior upper teeth and posterior lower teeth. This pacifier, as disclosed by Alanen et al., is more of a functional appliance, which moves bone.
Another problem associated with these pacifiers is that when the tongue is pulled back during a sucking action, the pressure that was created between the tongue and pacifier as well as between pacifier and palate pulls on the soft tissue of the palate which will in turn pull on the bone of the palate. Eventually, the palate will begin to collapse which can cause a crossbite.
A further problem associated with pacifiers is that they prevent the ordinary growth of the front teeth. The teeth ordinarily erupt until they meet an opposing force to prevent further growth, which is generally the opposing teeth. When a pacifier is placed between the front teeth, the jaw is effectively propped open. When the jaw is propped open for extended periods of time, the posterior molars continue to erupt while the front teeth are prevented from erupting because of the pacifier, which leads to an open bite where there is a vertical gap between the front teeth or a large overjet. After the infant reaches the age of two, the open bite is difficult to correct.